Add missing return code check on calls to mbedtls_md()
diff --git a/tests/suites/test_suite_ecdsa.function b/tests/suites/test_suite_ecdsa.function
index ab3db3a..59c1c49 100644
--- a/tests/suites/test_suite_ecdsa.function
+++ b/tests/suites/test_suite_ecdsa.function
@@ -500,7 +500,9 @@
     TEST_ASSERT( md_info != NULL );
 
     hlen = mbedtls_md_get_size( md_info );
-    mbedtls_md( md_info, (const unsigned char *) msg, strlen( msg ), hash );
+    TEST_ASSERT( mbedtls_md( md_info,
+                             (const unsigned char *) msg, strlen( msg ),
+                             hash ) == 0 );
 
     mbedtls_ecp_set_max_ops( max_ops );